Locking pliers such as the many varieties of locking pliers sold by the Petersen Manufacturing Co., Inc. of Dewitt, Nebr., under the trademark Vise-Grip offer significant advantages to the user in many situations. Locking pliers are described in U.S. Pat. Nos. 2,280,005; 2,514,130; 3,192,804; 4,541,312; 4,546,680; 4,709,601; 5,056,385; and others identified in these patents.
In certain locations, it is awkward or dangerous to use a locking pliers such as where there is moving machinery, heat, electricity, limited access, or a remote position. For example, the smog testing of automobile engines requires attaching a wire lead to a spark plug while the engine is operating and hot. Vacuum and water hoses are clamped shut for some tests while the engine is operating. Locking pliers having the handle remotely located from the jaws would be useful for these conditions.
Extensions for locking pliers have been developed as shown in U.S. Pat. Nos. 4,462,284 and 4,519,278. Both are for manipulating unmodified locking pliers from a distance. The device in U.S. Pat. No. 4,462,284 has an extension handle for each handle of the locking pliers. The resulting overall arrangement is cumbersome. The device in U.S. Pat. No. 4,519,278 requires the locking pliers to be attached to the work piece first and then manipulated from a distance later. Both of these devices therefore have only limited usefulness.
Extensions for non-locking pliers are more prevalent. U.S. Pat. No. 1,519,938 illustrates a pliers having a flexible tube connection between the handles and jaws. A wire inside the tube connects one of the handles to one of the jaws. When the handles are squeezed, the handles pull the wire forcing the jaws together. The pliers have limited utility because the flexible connection between the handles and jaws makes the positioning of the jaws difficult from a distance.
Extension tools having rigid connections between the handles and jaws are easier to position from a distance. All of the devices in the following patents have rigid tubes between the handles and jaws and rigid rods inside for transmitting the motion from the handles to the jaws. The tool in U.S. Pat. No. 1,992,596 has a spring loaded depression button on one end and jaws on the other. When the button is depressed, the fingers open. When the button is released, the spring forces the button back clamping the jaws on a work piece. Of particular interest is the connection between the rod and jaws. The rod projects past the pivot points of the jaws and is connected to each jaw by a rigid hinged link attached to the jaw by a pivot located on the jaw past the end of the rod. The resulting arrangement causes the jaws to open when the button is pushed.
U.S. Pat. No. 2,518,994 discloses a forceps having a rod that closes the jaws by means of an inclined cam operating against one of the jaws. One of the handles pushes the end of the rod. Because of the inclined surface of the rod, the rod must not be allowed to rotate out of proper alignment with the jaw. Of particular interest is the means for maintaining alignment. A pin passes through the walls of the tube and a slot in the rod keeping the rod in alignment with the tube. U.S. Pat. No. 2,532,972 shows a different cam arrangement. The jaws pivot past the end of the rod and each have cam faces. The end of the rod is a cone. When the rod is pushed downs the cone operates against the cam faces closing the jaws. U.S. Pat. No. 2,827,694 shows a tool having a handle that pushes on the end of the rod to engage a contact ball which operates against a cam face on the jaw. Of particular interest in this tool is a threaded quick coupling for changing jaws.
No combination of a locking pliers having the jaws remotely located from the handles has been developed. Such a combination would have many useful purposes.